Electric Kart catching fire. Help!!!

[onklsven75]

I'm in need of some advice.
I have an electric kart powered with 2 12v deep cycle boat batteries wired to make a 24v system.

I have a momentary pushbutton switch wired into the positive line between the battery and motor. Over time this button starts on fire and melts.

Obviously I'm doing something wrong. Can anyone provide any suggestions to get me going in the right direction?

 

[KieranM]

Are you sure you have it wired correctly?

Have you tried rearranging the wires? this might help.

Also your switch might not be able to handle 24v

 

[Fawteen]

The switch isn't designed to handle that much current.

Use the switch to energize a starter solenoid. A relatively low current will hold the solenoid closed.

Any solenoid off a lawn tractor or even an older car will work. Run a #12 wire from the + side of the battery to the switch, and from the switch to the coil on the solenoid. Ground the solenoid to the frame.

Then run the main battery cable to the big post on the solenoid and another cable from the other side of the solenoid to the motor.

Thinking about it, you might want to use the biggest solenoid you can find, as they're really designed for 30 seconds or so to turn a starter motor. Eventually, constant use will toast a solenoid too, but they'll last MUCH longer than your pushbutton switch.

 

[onklsven75]

Thank you! I'll give that a try.

 

[jr dragster T]

Interesting post Fawteen, I made a electric scooter (Look under electric section here and click on my electric scooter project). I started out with a ford starter solenoid and I melted that shut as soon as it cooled down. I then whent to canadian tire and bought a RV battery switch over solenoid. Its completly made of steel and I've been using this with great success and the solenoid after many cycles on and off for about 5-10 minutes at a time just barely gets warm.

http://www.neon-john.com/RV/Electrical/isolation_relay02.jpg

 

[frederic]

That would have been my suggestion.... an automotive starter relay.

 

[Fawteen]

I then whent to canadian tire and bought a RV battery switch over solenoid. Its completly made of steel and I've been using this with great success and the solenoid after many cycles on and off for about 5-10 minutes at a time just barely gets warm.

http://www.neon-john.com/RV/Electrical/isolation_relay02.jpg

That's good to know, I'll keep that in mind!

 

[anderkart]

Interesting post Fawteen, I made a electric scooter (Look under electric section here and click on my electric scooter project). I started out with a ford starter solenoid and I melted that shut as soon as it cooled down. I then whent to canadian tire and bought a RV battery switch over solenoid. Its completly made of steel and I've been using this with great success and the solenoid after many cycles on and off for about 5-10 minutes at a time just barely gets warm.

http://www.neon-john.com/RV/Electrical/isolation_relay02.jpg

Those all metal RV solenoids are primarily used for dual battery setups and are designed for continuous duty. Most any good auto parts store should stock-em.

To wire one of these up you'd connect your 12 (or 24 volt) + battery source to the large left side terminal and your motor to the large terminal on the right side. To trigger the solenoid either one of the 2 small terminals needs to be grounded and then the other small one should receive a 12 volt signal, not 24. (so wire your push button switch to the first of your series wired batteries + terminal to achieve the switches 12 volt power source)

Those simalar looking plastic Ford style, starter solenoids (and most others made for starting a car) are only designed for momentary type service. They have a pull in coil but not a hold in type coil inside. They'll work for awhile but most all of these types tend to overheat and malfunction after a short time when used for a continuous duty application like your situation.

 

[anderkart]

Another more simple option would be to install a foot operated starter switch like this: http://cgi.ebay.com/Foot-Operated-Starter-Switch-New-Cole-Hersee_W0QQitemZ250428983542QQcmdZViewItem
(this would also be safer leaving both hands avalible for steering)

These were commonly used on older cars, trucks and tractors and they're designed to handle a high amperage draw at most any voltage. You'd simply run your 24 volt + battery cable to either terminal and then the other would be connected to your motor.

With the 1000 or more cranking amps avalible from the 2 batteries your using, and also depending on the amperage draw of your motor, I'd suggest you wire everything up with 6 gauge or preferably larger battery cables to reduce voltage drop. Probably wouldnt hurt to also have some sort of battery cable quick disconect in close reach of you just incase the contacts became stuck together in your solenoid or foot start button...

 

[jr dragster T]

I have put 24 volts on the coil now for a long time on the RV solenoid with no issues at all. This is a solenoid too, Just a push button type on my JR dragster starter.

 

[anderkart]

Yeah you can connect any DC voltage level through the 2 big posts, I just recommended he run a 12 volt trigger signal from his push button switch to match what an RV solenoids is usualy rated at. The small terminals on RV solenoids dont make any direct connection to the big outer battery posts.

Kart starter solenoids with push buttons like yours aren't called RV solenoids, this type were origanaly used on older tractors. They dont have any pull in or hold in coil, just a mechanical set of contacts.
Looking at the way yours is connected up, it looks like they're triggering the ground side through it. That's a good idea, there's less out there for anything metal to contact and become a welder.

Using one of these would be a good option for onklsven75.

 

[jr dragster T]

Yeah, The kart starter switch is not realy called a RV solenoid I know. I like it because theres no coil to burn up and theres no excess load that a coil takes. It takes about 2 amps just to throw the coil on my old starter solenoid.